Abstract
This report summarizes one year of pre-construction data collection for avian abundance, use, mortality, raptor nesting, and prey availability at the Ponnequin Wind Energy Project site and two nearby reference sites. The project owners have funded data collection on the area proposed for project development since June 1997. Data collection on the reference sites was funded by the National Renewable Energy Laboratory (NREL) for one year of study, January through December 1998. The project site is in Weld County, Colorado, just south of the Wyoming border. Reference sites are situated immediately to the west of the project site (Weld County) and 4.8 kilometers (km) (3 mi.) to the north of the project site (Laramie County, Wyoming). Data collection on the project and reference sites continues under the funding of the project owners.
Metrics and data collection methods established for the Ponnequin project site in June of 1997 were used for the reference sites so that methods would be identical. Avian survey methods included two main transects of more than 800 meters (m) at each site, with two 400-m perpendicular transects on three of the sites and one 400-m perpendicular transect on one site. Thirty-one avian surveys were completed on the reference site from January to December 1998. Prior to the start of construction on the project site, 29 surveys were completed on the project site from mid-September 1997 to mid-September 1998. Birds of all types and their behaviors were noted. Surveys of prey availability were conducted April through August 1998 along all four main transects. Carcass searches, with affiliated observer efficiency and carcass removal (scavenger) evaluations, were conducted.
The surveys revealed no endangered, threatened, or species of concern on the project or reference sites. Species composition and abundance patterns of songbirds and raptors on reference and project sites are presented, as are basic use patterns. Horned Lark and McCown's Longspur accounted for 85% of all songbirds observed on the project and reference sites. The Golden Eagle, Swainson's Hawk, and Ferruginous Hawk accounted for 75% of all raptors observed on both sites. Most raptors were observed at distances > 1 km from all transects. Few raptors were observed hunting along the main or perpendicular transects.
Potential prey species consisted primarily of thirteen-lined ground squirrels and northern pocket gophers. Abundance indices were determined for these species during their active period (April through August) for comparison with the post-construction study period. Surveys demonstrated that the abundance patterns varied along given transects.
Pre-construction carcass surveys revealed two avian (Horned Lark and Western Meadowlark) fatalities. Carcass search efficiency studies were conducted during August, with efficiency rates varying with the size of carcass: one-quarter of small songbird-sized carcasses, three-quarters of mid-sized (small ducks, rails, and small hawks) carcasses, and all large (large waterfowl, owls, and hawks) carcasses were detected. The efficiency rates of two field technicians were also measured. Carcass removal was rapid for small birds (1 to 3 days), but large carcasses were detectable for more than one to two months.